Nitrogen-rich metal-organic framework for CO2 capture

“The high porosity and stability together with the coordination-free triazole moieties and open metal sites are favorable to the interactions between gas molecules and the framework of NTU-105, which inspired us to investigate its gas uptake capacity and selectivity towards CO2. As shown in Figure 3, CO2 sorption isotherms reveal an uptake capability of NTU-105 as high as 187 cm3 g−1 (36.7 wt%) at 1 atm and 273 K, which makes NTU-105 a top MOF material for CO2 uptake reported to date17,18, including its isoreticular MOFs containing acylamide groups, amine units, or triazine moieties (i.e., 42.6% for Cu-TPBTM39 and 44.5% for Cu-TDPAT41). For comparison, the N2 uptake of NTU-105 at 273 K and 1 atm was measured to be only 16 cm3 g−1. The high adsorption selectivity of NTU-105 towards CO2 over N2 under the same conditions (Figure 3) indicates that NTU-105 is highly applicable in the separation of CO2 over N2. Then, the isosteric heat of adsorption (Qst) for CO2 was calculated based on the adsorption isotherms at different temperatures (273 and 298 K, Figure S11 in the SI) through Clausius-Clapeyron equation17. It was found that Qst is ~35 kJ mol−1 at low loading range, followed by the convergence into a pseudo-plateau (~24 kJ mol−1) with relatively high uptake, the observations which are indicative of strong CO2-framework interactions. The Qst value at low loading range is the second highest one among the reported rth-MOFs, while Cu-TDPAT presents the highest value (42.2 kJ mol−1) so far41.”



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